textproduct: Rapid City

KEY MESSAGES

- Isolated severe storms are possible over south central SD late Tuesday evening. Main hazards will be large hail and damaging winds.

- Unsettled weather continues through the rest of the week with near daily chances for isolated afternoon showers/storms and temperatures in the 80s to 90s.

UPDATE

Issued at 1041 PM MDT Mon Jun 29 2026

Wind Advisory and Red Flag Warning were allowed to expire as scheduled this evening, and no major changes were made to the forecast with this evening's update. Next chance of showers and a few thunderstorms still looks to hold off until after 5-6 PM Tuesday evening starting along the Nebraska border. Tuesday will still be breezy and dry with near-critical fire weather conditions in roughly the same corridor as today's Red Flag Warning (northeast WY south of Gillette and Newcastle into southwestern SD and the Badlands), but winds will be lower and much more marginal. Will continue to monitor any trends.

DISCUSSION

(This Evening Through Monday) Issued at 112 PM MDT Mon Jun 29 2026

Current upper level analysis depicts upper low centered over MT with 90-100KT 300 mb jet streak over WY/CO. Water vapor imagery shows dry air streaming into western SD ahead of another weak wave associated with the aforementioned jet streak. Most areas will remain dry today though isolated to scattered showers/storms are possible over northwestern SD this afternoon and evening as the jet streak moves overhead. Ample deep layer shear of 50+KT will support rotating updrafts and organized severe weather, though forecast ML CAPE values will be 500-1000 J/kg which will limit overall severe threat. Still, we could see a couple of stronger to severe storms with large hail and damaging wind gusts as the main hazards. Southwest winds are picking up across the region with gusts of up to 50-55 mph in WY. These winds will move over western SD later this afternoon, a Wind Advisory remains in effect for much of the western SD plains.

Unstable southwest flow continues across the Northern Plains through Tuesday with another shortwave approaching the region late Tuesday into early Wednesday. This should bring another round of convection to our corner of the plains late Tuesday night/early Wednesday morning. In terms of severe threat, some elevated instability could push into our south central zones late Tuesday evening with forecast MU CAPE approaching 3000+ J/kg. Deep layer shear will be marginal (around 20-30 kt) so not expecting any widespread organized severe weather but we could see isolated elevated storms capable of large hail and damaging winds.

Storm chances continue through Wednesday as a weak wave approaches the region. Again, the higher instability will be displaced to the south of our CWA but forecast ML CAPE of 1000-1500 J/kg and 40-50kt of deep layer shear may be enough to support an isolated severe threat Wednesday afternoon and evening. Looking into the holiday weekend, models are still indicating warming temperatures through the end of this week with highs in the upper 80s to 90s by Friday. Continued southwest flow across the Northern Plains will support near daily chances for afternoon storms as upper level disturbances ripple along the flow.

AVIATION

(For the 06Z TAFS Through 06Z Tuesday Night) Issued At 1042 PM MDT Mon Jun 29 2026

VFR conditions are expected through most of the forecast period. Isolated showers and thunderstorms are possible across portions of northeast Wyoming, southwestern South Dakota, and into central South Dakota starting around 01/00-02z. Transient MVFR conditions are possible with these showers/thunderstorms. Gusty (~30kts) west winds will develop mid-morning across northwestern South Dakota and last through 01/00-02z.

FIRE WEATHER

Issued At 112 PM MDT Mon Jun 29 2026

Humidities over Southern Campbell County into southwestern SD have dropped into the teens to low 20s with increasing southwest winds. Widespread critical fire weather conditions expected this afternoon across those areas as humidities drop to around 15 to 18% and southwest winds gust up to 55 mph. Elsewhere, elevated to near-critical fire weather conditions expected to develop this afternoon.

Elevated to near-critical fire weather conditions expected again tomorrow as humidities drop to 15 to 20% across much of the area. Lighter winds will preclude the development of critical fire weather conditions, though localized critical fire weather conditions may develop over northwestern SD where westerly winds may gust up to 40 mph.

Daily elevated to near-critical fire weather conditions anticipated through the latter half of the week, especially over northeastern WY into southwestern SD as temperatures climb into the 90s and humidities drop into the teens to low 20s.

UNR WATCHES/WARNINGS/ADVISORIES

SD...None. WY...None.